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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="=text/css">
        tr:first-child>td::after{
            content: "表头";
           
        }
        tr:nth-child(n+2)td::after{
            content:"单元格"

        }
        tr+tr>td::after{
            content:"单元格"
        }
        tr:nth-child(even){
            background-color: skyblue;
        }

    </style>
</head>
<body>
    <table border="1" cellspacing="0" width="300px"height="200px">
        <tr>
            <td></td>
            <td></td>
            <td></td>
            <td></td>
            <td></td>
        </tr>
        <tr>
            <td></td>
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        </tr>
        <tr>
            <td></td>
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        </tr> 
        <tr>
            <td></td>
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        </tr>
        <tr>
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        </tr>
</body>
</html>